Insert for dental flasks



Nov. 13, 1951 L. SCHIARFE INSERT FOR DENTAL FLASKS Filed July 10, 1950 AE mm EH mm m HM A TTORNEY.

Patented Nov. 13, 1951 UNITED STATES PATENT OFFICE i Y 2,574,594,", i

INSERT or; DENTAL FLnsKs Le ischa ltimo M Apr p i n Ju y 1. Q, Serial;No. 172,943 7 This invention relates to dental equipment and more particularlyto details pertaining to the flasks used for molding dental plates.

' It iscustomary to pour liquid plaster of Paris or similar composition into a flask, in which a dental matrix has been arranged, so that the resulting hardened stone will be set in all around the latter and attached to the inside surfaces of the flask, for handling in the layer processes employed for making the dental plate. It is usual afterwards to remove the stone or plaster by sawing it out. This is'a long process and is of such 30, 1949, respectively, provided wedge-like lugs fixed on the inside wall surface of the flask used, which set in the plaster or composition. After the plaster was hard and its general purpose accomplished, the stone material was readily removed by exerting pressure with a tool near the apex or apices of the lugs suflicient to continue it into a crack resulting in the plaster, and permit its being-broken into removable pieces. These pieces were easily removed without damage to the matrix or the plate formed inside. This in- A vention is an improvement of this previous arrangement, and is particularly intended for use with conventional flasks that do not have these lugs previously formed in them. It consists of a liner band of thin and resilient material inserted against the inside surface of the flask and provided with slidable wedges or clips to be used in place of the fixed lugs previously invented, and serving the same purpose. However the wedgeclips are adjustable around the band and may be attached on and removed very easily.

It is therefore an object of the invention to provide a new and improved liner for dental flasks that will have unique advantages and features not previously known to the art.

Another object of this invention is to provide a new and improved liner for dental flasks that can be used with conventional dental flasks for the release of the plaster of Paris, or composition used for casting or molding therein, after it has completed its general purpose at the time and the particular flask is to be made available for reuse.

A further object of the invention is to provide a new and improved liner for dental flasks that 1 Claim. (01. 1873-3) will have an arrangement for the placement of wedge pieces thereon and provide for their spaced adjustment around the liner. An additional object of this invention is to provide a new and improved liner for conventional dental flasks that can be readily inserted or removed therefrom without the need of screws or other extraneous fastenings.

Still another object of the invention is to provide a new "and improved lining device for a dental mold flask that will facilitate removal complete with mold from the flask when the mold is tobe worked on. v

Other objects of the invention will be evident as the invention isjoutlined more in detail.

' Figure 1 is a plan view of a detachable liner for dental flasks and embodying this invention, the liner being shown in place in a flask indicated in dotted outline Figure 2is' a'plan view of the liner embodying this invention, a dotted outline indicating its resilient movement; and

Figure 3 is a sectional view taken along line 3-3 of Figure 2; and

Figure 4 is a section along line 44 of Figure 2.

Similar parts throughout the figures are designated by the same reference numerals.

The particular'form of the invention shown is that of a liner for insertion in a conventional dental flask and consists of a thin flexible band Ill, preferably of metal, its width being the same as the depth of the inside wall of the flask and bent to conform thereto. The band Ill is contoured like the flask so as to fit it neatly and is non-continuous. In this non-continuous form, it is easier to remove and insert it in the flask, and it allows for normal expansions and contractions. It also facilitates the placement of the wedgelike clips H on the band, as they can be slipped on from either open end, besides being attachable by crimping in place in the more laborious method. The band In is formed to provide a wall tapering downwardly, so as to enable it to slide in and fit the flask more easily.

The wedge-like clips H are made with two angular side walls l2 coming together in an apex.

- Flanges 13 extend laterally from the opposite edges of these walls so as to flt flat against the inside surface of the band, while the wedge 01' apeXed portion projects inwardly, leaving a hollow space M behind the latter. The clips'are made of a depth that is of the same dimension as the width of the band. The flanges are extended into fastening pieces l5, at the top and bottom. These pieces are bent over the edges of the band frictionally tight, but not so tight that they cannot be adjusted longitudinally along the band. The clips are located at strategic places on the band where they will not interfere with the insertion and placement of the matrix therein. At these locations the wedgelike pieces project into the plaster or composition afterwards poured into the flask and form a V-like cut from the peripheral side of the molding or casting composition rendering it easily breakable at the apex of the cut, by reason of its impress in the composition before setting into stone. is broken out of the stone, other pieces are readily broken off, and then the band can be manipulated to help in the process. The clips I l are made in several lengths and heights to suit the matrix and other conditions arising in the use of the flask. However ordinarily all the clips used in a particular flask, at a particular time, are of the same wedge depth.

The composition used may get into the hollow space I4 behind the clips ll, without obstructing its use in any manner, and is readily cleaned out when the liner isremoved if desired. The liner may not be removed in many cases after placement in the flask, but usually there is an advantage in doing so after every individual useas it enables the casting stone to be broken up more quickly, and the flask cleaned from all traces of the stone. The clips offer the desirable feature of being adjustable along the band before the casting or molding is proceeded with, so that any peculiar feature of the matrix or object used in the cast material can be provided for, in a very expeditious and convenient manner by predetermining the lines of severance. If any clip is broken or damaged, it can be readily replaced. The liner and its components are easily manufactured. They are relatively inexpensive. They make the conventional flask better and easier to use. They also reduce the possibilities of damage When a piece resulting to the dental plates caused in general practice, without their use. The liner being of thin and smooth material, enables its removal under the action of a press, to be accomplished easily and safely, since the liner will have little frictional resistance to obstruct this. This is because the stone or composition does not stick to the walls of the flask, as previously done, but to the removable band, which comes out relatively easily. Since pressure comes on the band instead of the stone, a great source of breakage is avoided.

While but one general form of the invention is shown in the drawings and described in the specifications, it is not desired to limit this application for patent to this particular form, as it is appreciated that other forms of construction could be made that would use the same principles and come within the scope of the appended claim.

Having thus described the invention, what is claimed is:

A liner for dental flasks adapted to contain a molding composition, said liner comprising an open-ended, arcuate, one-piece band, normally open at both its free ends, said band being flexibly compressible to fit within the inner walls of the dental flask, until its free ends lie in adjacency, and means on said band protruding inwardly therefrom towards the contents of the flask to form points of severance of the contents upon hardening thereof, said means consisting of pointed pieces having bendable portions adjustable on said band, whereby the pieces are adjustable on the band to selectively vary the point of severance.

LEO SCHARFE.

REFERENCES CITED The following references are of record in the file of this patent:

UNlITED STATES PATENTS 

